If you look at a bottle of ibuprofen, you know exactly what you are getting: 200 milligrams. It is measured by weight. But if you look at a bottle of digestive enzymes, you won’t see milligrams. Instead, you get an alphabet soup of letters: IU, SU, AGU, ALU.
Why? Because enzymes are not measured by how much they weigh; they are measured by how much work they can do.
Think of it like a car engine. You don’t judge an engine by how heavy it is—you judge it by its horsepower. For enzymes, these units measure their “digestive horsepower.”
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Note: not all enzymes are measured using the same type of units. Last Updated: April 2026
What exactly is an “Enzyme Unit”?
In chemistry, an enzyme unit measures speed and efficiency. Specifically, it measures how much of a sugar (the substrate) the enzyme can break down in exactly one minute.
However, enzymes are notoriously picky. They only work well under specific conditions. To measure an enzyme’s “horsepower” in a lab, scientists have to set a specific temperature and a specific acidity (pH) level.
This is where comparing products gets tricky. If Company A tests their enzyme at a pH of 4.5, and Company B tests theirs at a pH of 5.0, their numbers won’t match up perfectly. It is like comparing the top speed of two cars, but one was tested on a paved track and the other on a dirt road.
The “Alphabet Soup” of Measurements
Because different enzymes do different jobs, they each get their own specific type of unit. Here is your pocket translator for what those letters actually mean:Many of the high-quality supplements use standardized testing from the Food Chemical Codex (FCC). (Note: If you see a little “Δ” symbol on Klaire Labs products, that is just their footnote confirming they use FCC standards).
For Sucrose & Maltose (Invertase)
SU (Sumner Units): The standard measure for Invertase. One SU is the exact amount of enzyme needed to convert 1 milligram of sucrose into safe glucose and fructose in 5 minutes (at 20°C and 4.5 pH).
DP° (Degrees Diastatic Power): Used to measure how well an enzyme breaks down starches into reducing sugars.
For Starch (Amylase & Glucoamylase)
AGU (Glucoamylase Units): Measures how much glucoamylase is needed to liberate specific molecules in one minute at 50°C.
DU (Dextrinizing Units): Measures alpha-amylase activity—specifically, how fast it can break down soluble starch at 30°C.
For Dairy (Lactase)
ALU (Acid Lactase Units): Measures the quantity of enzyme required to break down lactose at normal body temperature (37°C) in a slightly acidic environment.
A Warning About “IU” and “U”
Some products just list “U” or “IU” (International Units). This is actually an outdated scientific standard that was officially superseded in 1999 by a new measurement called the katal. However, the supplement industry moves slowly, and many labels still use “IU”. Complicating things further, some brands use “IU” to simply mean “Invertase Units.” When in doubt, look for products that clearly list SU, AGU, or ALU, as these are much more precise.